The present invention relates generally to patient ventilation systems and, more particularly, to a modular compressor assembly which can be assembled using a baseline or common motor assembly to which can be mounted various sizes and configurations of blower housings in order to achieve different flow capabilities for the compressor assembly.
Blowers are commonly used in mechanical ventilators to generate compressed air for delivery to a patient. Such blower assemblies may comprise a blower housing having a blower inlet and a blower outlet. The blower assembly includes a motor assembly mounted within the blower housing and which is coupled to an impeller which draws air into the blower inlet. The air is compressed as it flows through the impeller and enters an annular chamber or volute after which the air is discharged from the blower outlet.
The motor assembly may be provided in a variety of alternative configurations such as a conventional brushed D.C. motor or in a brushless configuration. Because of their high operating efficiency under low-load conditions, brushless D.C. motors are particularly well-suited for use in generating compressed air. As such, brushless D.C. motors are commonly used in miniature fans and other blower configurations including certain ventilatory applications such as in CPAP devices for treating obstructed sleep apnea (OSA).
A further advantage of employing brushless D.C. motors in blower assemblies for CPAP devices is the reduced amount of vibration, heat and noise generated during operation which allows the use of CPAP devices in sensitive environments such as intensive care units (ICU) rooms or in a bedroom of a respiratory care patient. Furthermore, compressor assemblies powered by brushless D.C. motors may be packaged in very small sizes having low weight which, in association with their other advantages, makes them ideal for use in portable or wearable CPAP devices.
However, compressors used in CPAP therapy must be capable of generating different flow rates depending upon the type of respiratory treatment to be provided as well as the respiratory condition and physiological size of the patient. For example, patients undergoing CPAP treatment can range from pre-term infants, neonates and pediatric patients up to full-grown adult patients. As may be appreciated, the pressurized gas requirements of a neonatal patient differ markedly from the pressurized gas requirements of a full grown adult. Flow settings for neonates can be as low as 2 liters per minute (LPM) at pressures as low as 5 cm H20 as compared to the flow settings for a full grown adult patient requiring flow rates of up to 120 LPM and pressure settings of 20 cm H20 and higher.
As a result of these differing flow requirements, different compressor assemblies are designed for use with a certain range of flow settings. The compressor assemblies are optimized to produce the desired flow requirements at maximum operating efficiency and with minimal power consumption. In this regard, a common practice in the industry is to develop and manufacture a specific compressor assembly which produces optimal flow characteristics for a specific set of patient types and/or flow settings. As may be appreciated, the need to design, test and manufacture completely different configurations of compressor assemblies for different patients having differing flow requirements substantially increases the overall cost of CPAP devices.
As can be seen, there exists a need in the art for a compressor assembly having the capability to efficiently produce a broad range of flow characteristics (i.e., flow rate, pressure) for specific patient applications at a substantially reduced cost to the manufacturer and, ultimately, at a reduced cost to the consumer.